The invention relates to a technology for producing polymer materials, including textiles, with reduced combustibility, low toxicity of the gases given off during combustion and low smoke-forming capability.
Chemical fibres and textile materials are used in various industries, including for making composition materials used in road transport and in aircraft and ship building. Woven and knitted fabrics are used as decorative finishing materials in places where people are present in large numbers (theatres, clubs, hospitals, museums and hotels), in the building industry and in transport.
Textile materials are widely used in everyday life and for making special clothing for workers in practically every industry.
At the same time, the easy flammability and combustibility of most industrially produced chemical fibres and textile materials constitute a significant problem. They have a low spontaneous combustion temperature and a high burning rate.
A method of fire protection impregnation based on the use of orthophosphoric acid and compounds containing nitrogen (dicyanodiamide, carbamide, melamine, guanidine etc.) is widely used on an industrial scale in Russia. In this method, the fabric is treated with a composition including phosphoric acid and one of the listed
nitrogen-containing compounds and is subjected to heat treatment (Ye. A. Blekhman, The Manufacture of Incombustible Cotton Fabrics, Moscow, 1950-189 pp.). This process has considerable faults, namely a marked reduction in the resistance of the fabric to tearing load (a reduction in tearing strength of 40-50%) and low efficiency of the fire resistance effect for fabrics composed of a mixture of synthetic and cellulose fibres.
There is a known fire protection composition (GB application 2273720) for the treatment of fabrics, non-woven materials and carpet products, consisting of an aqueous solution of inorganic salts (ammonium phosphate, ammonium sulphate, ammonium bromide and mixtures of these in quantity 12-20% of the composition) and mineral acid (sulfuric acid-xe2x80x940.4-0.6 wt. % of the composition), which assists the solution in penetrating into the fibres of the material and which raises the stability of the bonding of the combustion retarder with the fibres of the textile material. A fault of this composition is the low efficiency of the fire protection effect for materials containing synthetic fibres.
The compositions FR Cros 282, 330 and 334, based on ammonium polyphosphates (Catalogue of Combustion Retarders, Bolid GmbH, Frankfurt, 1996), are used for the fire protection of textiles. The composition FR Cros 282 includes modified mono ammonium phosphate with 10% ammonium polyphosphate in combination with melamine and pentaerythritol in the ratio 3:1:1. The concentration of this composition in the aqueous suspension used for the treatment of textiles is 500 g/liter.
The composition FR Cros 330 is an aqueous vinyl acetate suspension with ammonium polyphosphate, in which the content of the solid matter is 50%. The composition FR Cros 334 includes modified ammonium pyrophosphate. It is used for the fire protection of wood, paper and textiles. For all these compositions, the fire protection effect is achieved with the introduction of combustion retarders into the material in quantity 30-40%, which leads to a reduction in the physico-mechanical indicators and feel properties of the fabrics.
There is a known fire protection process for cellulose materials, based on the use of tetra-(hydroxymethyl)-phosphonium chloride (THPC) and polyfunctional compounds containing nitrogen, which has been given the name xe2x80x9cProbanxe2x80x9d (U.S. Pat. No. 2,912,466). To make cellulose materials fire-resistant by this process, a polycondensation process is first carried out between THPC and carbamide at a molar ratio of the components of 1:1. The cellulose material is impregnated with an aqueous solution of the precondensate and dried.
The formation of a polymer insoluble in water and organic solvents is achieved by treating the material with ammonia solution or gaseous ammonia at 140-160xc2x0 C. This treatment is called xe2x80x9cProbanfinish-210xe2x80x9d. The problems with this method include a reduction in the strength of the fabric by 30% and an increase in the stiffness of the material. There are also data indicating high toxicity of the combustion products from cellulose materials containing THPC. When thermolysis of the fire-protected cellulose takes place in the 200-300xc2x0 C. range, the emission of phosphatin is observed (Spect. Chem., 1984, V. 4, pp. 17-20).
The most effective treatment for cellulose fabrics and for fabrics made of a mixture of cellulose and synthetic fibres is one called xe2x80x9cPyrovatex-CPxe2x80x9d (Technico-economic Information Bulletin on Light Industry, 1975, No. 9, pp. 75-76). The fabric is impregnated with an aqueous solution containing N-hydroxymethyldi-(methoxy)-phosphonopropionamide, carbamide, a cross-linking agent and a catalyst. It is then dried, heat-stabilised at a temperature of 140-160xc2x0 C. and washed. When cotton fabrics are treated by the xe2x80x9cPyrovatex-CPxe2x80x9d method, the fire-resistant properties are achieved at a content of 2.0% of phosphorus in the material.
The toxicity of the pyrolysis products of the materials is a significant problem for fabrics protected against fire by the use of N-hydroxymethyldi-(methoxy)-phosphono-propionamide. It has been shown (Textilveredelung, 1970, V. 6, pp. 486-497) that at a temperature of 300-400xc2x0 C., considerable quantities of methanol are emitted. The relationship revealed rules out the use of fabrics fire-protected in this way for making special clothing for workers and also for the fireproofing of materials used in enclosed spaces.
A study of the comparative effectiveness of the phosphorus-containing preparations xe2x80x9cProbanxe2x80x9d and xe2x80x9cPyrovatex-CPxe2x80x9d has shown that their effectiveness is different for cotton fabrics and fabrics made of a mixture of cotton and polyester fibres.
In all the studied variants of the treatment of fabrics made of a mixture of fibres by the xe2x80x9cPyrovatex-CPxe2x80x9d method, the materials had higher fire protection indicators. However, in both cases, fire-protected fabrics can only be produced if they contain not more than 10% of synthetic fibre (Text. Res. J., V. 45, No. 8, p. 586).
The main problem with the known xe2x80x9cProbanxe2x80x9d and xe2x80x9cPyrovatex-CPxe2x80x9d processes is their low effectiveness for materials made of a mixture of cellulose and synthetic fibres and pure synthetic fibres.
UK Patent 2205868 for the fire protection treatment of fabrics based on cellulose with other fibres proposes carrying out the xe2x80x9cProbanxe2x80x9d method treatment at least twice, and also oxidising the phosphorus into the pentavalent form by treating the fabric dried out after the first or second treatment with a solution of hydrogen peroxide.
U.S. Pat. No. 4,732,789 proposes a two-stage process of treating fabrics made of a mixture of cotton with polyester or nylon. The fabric is initially treated by the xe2x80x9cProbanxe2x80x9d method, after which hexabromocyclododecane or cyclic phosphonates are used to provide fire protection for the polyester or nylon components. The treated fabric is vulcanised, and if hexabromocyclododecane is used, it is heated to above 182xc2x0 C. to melt the fireproofing compound. The two-stage nature of the process and the requirement for vulcanisation at high temperatures makes it very difficult for this invention to be applied in practice.
A preparation called xe2x80x9cPyrofixxe2x80x9d, based on dialkyl phosphonamide of carbonic acid (Catalogue of Chemical Products, JSC xe2x80x9cIvkhimpromxe2x80x9d, 1995, pp. 22-23), has been proposed for imparting fire protection properties to textile materials containing cellulose.
To impart fire protection properties, it is recommended that the impregnating solution should contain the following (g/liter):
The problem with this preparation is the low efficiency of the fireproofing effect for fabrics made of a mixture of cellulose and synthetic fibres.
USSR Authorship Certificate No. 1427017 describes a fire protection treatment for textile materials using a composition including methyl phosphonic acid diamide, ammonium chloride, carbamide, glycazine or dimethyl polyethylene carbamide and sulfocide-31. The use of this composition makes it possible to obtain fire-protected textile materials made from a mixture of cellulose and synthetic fibres. The problems with this method are: the low hydrolytic stability of the methyl phosphonic acid diamide, and the instability of aqueous solutions containing both methyl phosphonic acid diamide and glycazine (the formation of a oligomer product insoluble in water, which has a low reaction capability relative to the functional groups of polymer materials). Fire-protected textile materials can only be obtained if there is a high content of combustion retarder on the fabric (up to 30% of the weight of the material).
Substance of the Invention Explained
Although there are known and widely used compositions of various kinds serving to reduce the combustibility of textile materials of natural (cotton, flax, wool) and chemical (viscose, cupro-ammonium, polyester, polycaproamide) fibres and mixtures of them in various compositions, the problem of creating new and more effective processes for the fire protection of materials and fire-protective compositions remains urgent. This invention is primarily aimed at solving this problem.
Other aims of the invention are:
to reduce the smoke-forming capability of fire-protected textile materials subjected to pyrolysis and combustion;
to increase the resistance of the fireproofing properties of the material to wet treatments and chemical cleaning;
to impart a range of fire-protection and water-and-oil-repellent properties to textile materials;
to enable these things to be done using simple and reliable equipment existing in the finishing production lines of textile factories.
The invention described below solves these problems.
The first aspect of this invention is the creation of a process for the fire protection treatment of textile materials which includes the following sequence of operations:
impregnation of the material with an aqueous solution of a melamine-type (melamine-formaldehyde) resin;
the drying of the material;
impregnation of the material with an aqueous solution containing carbamide and a complex compound of the ammonium salt of amidoalkylphosphonic acid with ammonium chloride, Formula 
where R is an alkyl radical with 1-3 carbon atoms;
the drying of the material and its heat treatment at a temperature of 140-170 C.
In addition to the operations listed above, the material may also be washed and dried after heat treatment.
Compounds containing silicon may be used instead of melamine-type resin for impregnating the material at the first stage of the fire protection process. Furthermore, these substances (melamine-type resin and silicon-containing compounds) may be used together.
Silicon-containing compounds, like melamine-type resin, are used in the textile industry as auxiliary substances at the final stage of finishing textile materials of various compositions. The presence of functionally active groups in the melamine-type resins and silicon-containing compounds makes it possible for them to interact both with the functional groups of the phosphorus-containing combustion retarder and with the functional groups of the macromolecules of the polymers in polycondensation reactions. The course of these reactions leads to a higher degree of fixation of the combustion retarder on the fabric and to greater resistance of the fireproofing effect to wet treatments and chemical cleaning. The combined use of melamine-type resins and silicon-containing compounds improves the feel of the fabric and its resistance to wear.
Another aspect of the invention is the creation of a composition for the fire-protection treatment of textile materials, which consists of an aqueous solution of carbamide and a complex compound of the ammonium salt of amidoalkylphosphonic acid with ammonium chloride as in Formula (I).
The advisable concentration of these components per liter of aqueous solution comprises:
To reduce the smoke-forming capability of the protected materials, it is advisable to add anion complexes of metals, in particular W, Zr and Ti, in a concentration of 2-10 g/liter.
To impart a range of fire-protection and water and oil repulsion properties to the materials, it is advisable to introduce latexes containing fluorine into the fireproofing composition in a concentration of 30-50 g/liter.
Furthermore, organosilicon substances may be introduced into the fireproofing composition as a water repellent.
The patent protection also extends to textile materials of natural fibres (cotton, flax, wool), of chemical fibres (in particular viscose, cupro-ammonium, polyester and polycaproamide) and mixtures of them of various compositions, if they are subjected to fireproofing treatment in accordance with this invention.